Does the D4 board fit any 20mm quad mcpcb or does it somehow only fit the D4?
Yes!
I used LED4Power Quad DTP Board
I should fit all 20mm quad boards which are quad TIR compatible, as this ensures the same hole spacing
I dont think it makes a difference that it’s a D4 but the tolerances for where the LED +/- are may not work for anything but a Noctigon 4XP. I guess YMMV. Maybe Lexel has tested others.
Edit: I see it works on L4P board. Looks less likely to work here:
true. That I did not think of! Sorry for my misleading post.
Perfect, thanks guys!
This is… seriously intriguing & inspiring. 
I wasn’t going to go with an Emisar… have Fireflies E07 on my horizon. If there’s definitely not going to be one of these TIR boards available for the E07, then I may have to shift gears. 
technically you dont need to screw down the aux board,
having it simply floating between optics and MCPCB, a few mm up are no problem to get the L4P board soldered,
you could also use some 3mm hole spacers to lift iut but got it screwed down
the E07 has already my board in the stock light, so there is no real need for me to order this board size
with LVP D4S, ROT66 and MF01 aux board from me available
D4 is simply stabilized with LDO, but can be build also without to support low mode
Really nice boards 
But tbh a lot of this goes over my head!
I disassembled my D4 recently to flash Anduril and found it very tricky to work with given the extremely limited space. I’m not sure I’ll have the skills or patience to take it apart again to add the aux cables. I really like the aux leds in my D4S though so I could be tempted.
The D1 TIR looks interesting as well. Do you have any more info on that?
Any plans to make one for the imminent release of the FW3A? 
D1 is not TIR its reflector with aux boards placed inside the gasket
I sanded that board to about 0.1mm thickness
the board with indirect gasket leds is not tested yet
Send me one and i’ll destroy my D1 for science:
LED Light Pipe + Dremel + UV Glue = ???
its meant to indirect light the white gasket
direct light version looks like this
I know, but why let it go to waste? The D1 doesn’t get that hot anyways I can make some holes, lol
edit; I mean in some cases they help cooling too…
Lexel - I's like to order a couple, maybe more, of these boards. I need one for my ROT66 (early version no AUX LED's), a D4, another quad, possibly an MF01, and possibly when you get the D1 ready. How does this work? pm you?
He will pm you for order details. Payment is through paypal.
Would this install in a D4 far surpass a newbies capacity? Super interested, but it might be a bit much to bite off.
It is not easy to install. The driver is hardly pressed in and there is verry less space for wires and soldering.
You will need a tiny wire for battery- on the aux-board. Battery+ is the same as LED+.
Usually most people do a reflash to D4S Firmware and use LED pin on driver for +
You could also flash Anduril for D4 with Aux support. D4S might work, but it’s not ideal as the part for the thermal regulation is made for a bigger part. Also the level mixing is off, as the D4S has more AMCs.
see here: How-To: D4 with Anduril + Aux support (windows)
But the whole process of installing (and flashing) is not a newbie task
So if I understand correctly, the LDO on the D4 TIR board causes it to have only one level of light? But if you took out the LDO then you could have low/high? I’ve never used aux lights before, so I’m basing it off of the H03 lexel driver with anduril, the light under the button has a few modes, high, low, flashing, off. Would this be the same with the stock D4 TIR board? Or would the LDO need removed? What are the implications of doing this?
I know I will need to flash the D4S firmware, or D4 anduril with the aux code added. But the LDO has confused me.
Sorry for all the questions, I want to learn, trying to understand.
Yes if you want high low then the LDO can be replaced with a resisor, which fits 0603 to get between the pads or build with resistors based on 3.7 not 2.8V
The LDO is to stabilize the current while battery voltage drops